Energy management system for a hybrid-electric vehicle

ABSTRACT

A system for optimizing electrical power management in a vehicle. The system includes a HVAC device and a thermal storage device, both configured to provide heating and cooling to an occupant compartment of the vehicle. The system further includes a controller connected to an electrical storage device and an electrical generating device. The controller receives electrical power generated by the electrical generating device and directs the electrical power to satisfy the vehicle&#39;s power requirements and/or stores the electrical power in at least one of the electrical storage device and the thermal storage device. Furthermore, the controller directs at least one of the HVAC device and the thermal storage device to provide heating and cooling to the occupant compartment of the vehicle, depending on the available storage of the thermal storage unit or occupant compartment demands.

BACKGROUND

1. Field of the Invention

The present invention generally relates to energy management systems of a vehicle, in more particularly to energy management systems of a hybrid-electric vehicle.

2. Description of the known technology

A hybrid-electric vehicle uses an electric motor in conjunction with a conventional internal combustion engine to create torque to drive its wheels. When the driver of the hybrid-electric vehicle applies the brakes, the hybrid-electric vehicle reverses the function of the electric motor, thus, turning the electric motor into an electric generator. As the hybrid-electric vehicle approaches the stop, the wheels of the hybrid-electric vehicle, in conjunction with the electric motor acting as an electric generator, generate a pulse of electrical power. This pulse of electrical power is stored in an energy storage device such as a capacitor or battery and later used to drive the wheels and/or power the vehicle accessories, such as a heating, ventilation and air conditioning (“HVAC”) system. However, because of the nature of the pulse, when storing the electrical power, some of the electrical power is lost due to parasitic losses.

The electric motor, acting as an electric generator, is not the only source of electrical power in a hybrid-electric vehicle. For example, an alternator and heat capture devices, such as thermoelectric devices placed on the exhaust of the hybrid-electric vehicle, may be utilized to generate electrical power. This electrical power may be stored in an energy storage device. Similar to the electrical power generated by the electric motor, some of the generated electrical power is lost due to parasitic losses.

When the hybrid-electric vehicle is at a stop, it is common for the hybrid-electric vehicle to shut down its internal combustion engine. However, when the HVAC system of the hybrid-electric vehicle is in operation, the hybrid-electric vehicle may have to drain the energy storage device and/or keep the internal combustion engine operating in order to keep the HVAC system running. These demands will decrease fuel economy.

Therefore, it is desire to provide a more efficient system for providing heating and cooling to the occupant compartment of the hybrid-electric vehicle while maximizing the storage of the pulse of electrical power generated during braking and by the other electrical power generated by the hybrid-electric vehicle.

BRIEF SUMMARY

In overcoming the drawbacks and limitations of the known technologies, a system method for managing electrical power generated by a vehicle is disclosed. The system includes a HVAC device and a thermal storage device both being configured to provide heating and cooling to an occupant compartment of the vehicle. The system further includes a controller connected to an electrical storage device and an electrical generating device. The electrical generating device may be several devices, such as an alternator, a regenerative braking generator and a waste recovery power generator. The controller will receive electrical power generated by the electrical generating device and store the electrical power in at least one of the electrical storage device and the thermal storage device. Furthermore, the controller will direct at least one above the HVAC device and the thermal storage device to provide heating and cooling to the occupant compartment of the vehicle.

As to the method, the method includes the steps of receiving electrical power, monitoring the available storage of the electrical and thermal storage devices and storing the electrical power received in at least one of the electrical storage device and the thermal storage device. Furthermore, the method may include the steps of storing the electrical power in the electrical storage device when the thermal storage device is at a maximum capacity and storing electrical power in the thermal storage device when the thermal storage device is below a maximum capacity.

The method may further include steps for providing heating and cooling to the occupant compartment of the vehicle. This includes monitoring the thermal requirements of the occupant compartment and providing heating and cooling to the occupant compartment from at least one of the thermal storage device and the HVAC device based upon the thermal requirements of the occupant compartment. If the thermal requirements of the occupant compartment can be met solely by the thermal storage device, the thermal storage device will provide the heating and cooling. However, if the thermal requirements of the occupant compartment will not be satisfied by the thermal storage device, the HVAC device may supplement the thermal storage device or solely provide the heating and cooling.

These and other advantages, features and embodiments of the invention will become apparent from the drawings, detailed description and claims which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an energy management system for a vehicle embodying the principles of the present invention; and

FIG. 2 is a block diagram of second embodiment of an energy management system for a vehicle according to the principles of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, the various components of an energy management system 10 for a vehicle according to one embodiment of the present invention are shown. The energy management system 10 includes a controller 12 connected to an alternator 14, a regenerative braking system generator 16, and a waste heat recovery system 18. The controller 12 may be one controller or multiple controllers in communication with each other.

The alternator 14 is preferably a belt driven alternator, driven by an engine (not shown) of the vehicle and has clutches that selectively create electrical power. The regenerative brake system generator 16 is preferably a regenerative braking system commonly used on hybrid-electric vehicles, which generate electrical power while the hybrid-electric vehicle is braking. The waste heat recovery generator system 18 is preferably a system for capturing heat created by the vehicle during operation. The waste heat recovery generator system 18 may be one or more thermoelectric modules located near areas of the vehicle which create heat, such as the exhaust and engine of the vehicle. Electrical power generated by the alternator 14, the regenerative braking system generator 16, and the waste heat recovery system 18 is directed to the controller 12.

The controller 12 is also connected to an electrical storage device 20 and stores electrical power generated by the alternator 14, the regenerative braking system generator 16, and the waste heat recovery system 18. The electrical storage device 20 is preferably one or more capacitors or batteries, but may be any device suitable for storing electrical power.

Connected to the controller 12 is a HVAC device 24. The HVAC device 24 is preferably an electrical HVAC device but may be a conventional belt driven device or any vehicle heating and cooling system that is now known or later developed. If a conventional belt driven HVAC system is utilized, a system of clutches may be implemented to selectively place the HVAC unit in an operating mode. One or more ducts 29 are coupled to the HVAC device 24 and direct conditioned, heated or cooled air from the HVAC device 24 to the occupant compartment 26.

A thermal storage device 22 is coupled to the HVAC unit 24. In certain situations described below, the HVAC unit 24 converts the electrical power directed to the HVAC unit 24 from the controller 12 into thermal power and stores this thermal power in the thermal storage device 22. Typically, one or more thermoelectric devices are utilized to convert the electrical power into thermal power but any suitable electrical power to thermal power conversion device may be used. In order to store the thermal power, the thermal storage device 22 may contain both a high and low temperature phase change material, such as wax (a high temperature phase change material) and water (a low temperature phase change material).

The energy management system 10 further includes an electrical storage level sensor 32 and a thermal storage temperature sensor 34 for determining the available amount of storage available for electrical and thermal power in the electrical storage device 20 and the thermal storage device 22, respectively. An occupant compartment temperature sensor 36 is connected to controller 12, such that the temperature of the occupant compartment can be monitored by the controller 12.

Last, the energy management system 10 further includes vehicle accessories 37 connected to the controller 12. The vehicle accessories 37 may include fuel injectors, interior and exterior lighting, vehicle information, entertainment and navigation systems or any electrical powered device found in the vehicle. The controller 12 direct electrical power to the accessories 37 as needed.

When in operation, the controller 12 will receive electrical power generated from at least one source, such as the alternator 14, the regenerative brake system generator 16 or the waste heat recovery system 18. The controller will monitor the available amount of storage remaining for electrical and thermal power storage by monitoring the output of the electrical storage level sensor 32 and the thermal storage temperature sensor 34, respectively. Based upon the remaining storage available in the thermal storage device 22, the controller 12 will direct the electrical power to either the electrical storage device 20 or the HVAC unit 24. The HVAC unit 24 will then function to convert the electrical power to thermal power and store the thermal power in the thermal storage device 22 for later use.

If the thermal storage device 22 has inadequate suitable storage for storing the thermal power, the electrical power will be directed to the electrical storage device 20. Alternatively, the controller 12 can direct a portion of the electrical power to be stored in the thermal storage device 22 and the rest of the electrical power to the electrical storage device 20. It is preferred to first store the electrical power in the thermal storage device 22, rather than the electrical storage device 20, because it is more efficient to store the thermal power in the thermal storage device 22.

The controller 12 will also monitor the temperature of the occupant compartment 26 via the occupant compartment temperature sensor 36 and direct the HVAC device 24 to provide heating or cooling to the occupant compartment 26. The HVAC may provide all or part of the heating and cooling to the occupant compartment 26 by using the thermal power stored in the thermal storage device 22 or may generate the required thermal power on its own. Also, the HVAC device 24 may supplement the heating and cooling it provides to the occupant compartment 26 with the thermal power stored in the thermal storage unit 22.

By having the thermal storage device 22 provide all or part of the heating and cooling to the occupant compartment 26, the vehicle may be able to not require HVAC device 24 to generate the necessary heating and cooling for extended periods of time. By minimizing the use of the HVAC device 24 for generating the heating and cooling, the vehicle will be able to achieve greater fuel efficiency.

Referring to FIG. 2, another embodiment of an energy management system 10′is shown therein, wherein similar reference numerals used in FIG. 2 denote identical components as in the embodiment of FIG. 1. The energy management system 10′differs from the one shown in FIG. 1 in that the thermal storage device 22 will receive electrical power directly from the controller 12, convert the electrical power to thermal power and store the thermal power. Furthermore, the HVAC device 24 and the thermal storage device 22 direct heated or cooled air to the occupant compartment 26 via separate ducts 28, 30, respectively.

The controller 12 is configured to determine if the occupant compartment 30 can be sufficiently heated or cooled by the thermal storage device 22 through the duct 28. If the occupant compartment 26 can be adequately heated or cooled by the thermal storage device 22, the controller 12 will direct the thermal storage device to provide the heating or cooling to the occupant compartment 26, while leaving the HVAC in an “off”state. However, if the controller 12 determines that the thermal storage device 22 is unable to provide adequate heating and cooling to the occupant compartment 26, the controller may direct the HVAC device 24 and the thermal storage device 22 to both provide adequate heating and cooling to the occupant compartment 26. Alternatively, if the thermal storage device 22 is unable to provide adequate heating and cooling to the occupant compartment 26, the controller may direct HVAC device 24 to solely provide heating and cooling to the occupant compartment 26.

The foregoing description of the embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiment disclosed. Numerous modifications or variations are possible in light of the above teaching. The embodiment discussed was chosen and described to provide the best illustration of the principles of the invention in its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particulate use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. 

1. An energy management system for a vehicle comprising: a heating, ventilation and air conditioning (“HVAC”) device to provide heating and cooling to an occupant compartment of the vehicle; a thermal storage device configured to provide heating and cooling to the occupant compartment of the vehicle; an electrical storage device; and a controller configured to receive electrical power from an electrical generating device, the controller connected to the electrical storage device and the HVAC device and configured to store the electrical power in at least one selected from the group of the electrical storage device and the thermal storage device.
 2. The system of claim 1, wherein the electrical generating device is at least one selected from the group of an alternator, a regenerative braking generator and a waste recovery power generator.
 3. The system of claim 1, wherein the controller directs at least one of the HVAC device and the thermal storage device to provide heating and cooling to the occupant compartment of the vehicle.
 4. The system of claim 3, wherein the thermal storage device provides heating and cooling to the occupant compartment of the vehicle via a duct coupled to the HVAC device.
 5. The system of claim 1, further comprising an occupant compartment temperature sensor connected to the controller for monitoring at least a portion of the occupant compartment of the vehicle.
 6. The system of claim 1, further comprising an electrical storage level sensor connected to the controller for monitoring the available storage of the electrical storage device.
 7. The system of claim 1, further comprising a thermal storage temperature sensor connected to the controller for monitoring the available storage of the thermal storage device.
 8. A method for managing thermal power flow in a vehicle having an electrical storage device and a thermal storage device and a heating, ventilation and air conditioning (“HVAC”) device, the method comprising the steps of: receiving electrical power from an electrical power generating device; monitoring the available storage of the electrical storage device; monitoring the available storage of the thermal storage device; converting the electrical power to thermal power; and storing the thermal power in the thermal storage device.
 9. The method of claim 8, further comprising the step of storing the electrical power in the electrical storage device when the thermal storage device has inadequate available storage.
 10. The method of claim 8, further comprising the step of storing the electrical power in the electrical storage device when the occupant compartment thermal needs have been met.
 11. The method of claim 8, further comprising the step of storing the electrical power in the thermal storage device when the thermal storage device has adequate available storage.
 12. The method of claim 8, further comprising the step of storing a first portion of electrical power in the thermal storage device and storing a second portion of electrical power in the electrical storage device.
 13. The method of claim 8, further comprising the steps of monitoring the thermal requirements of an occupant compartment of the vehicle and providing heating and cooling to the occupant compartment from at least one of the thermal storage device and the HVAC device based upon the thermal requirements of the occupant compartment.
 14. The method of claim 8, further comprising the steps of providing heating and cooling to the occupant compartment from the thermal storage device when the thermal power stored in the thermal storage device is at least equal to the thermal requirements of an occupant compartment of the vehicle.
 15. The method of claim 8, further comprising the step of providing heating and cooling to the occupant compartment from the HVAC device when thermal power stored in the thermal storage device is less than the thermal requirements of an occupant compartment of the vehicle.
 16. The method of claim 15, wherein the step of providing heating and cooling to the occupant compartment is provided solely from the HVAC unit.
 17. The method of claim 15, wherein the step of providing heating and cooling to the occupant compartment is provided from both from the HVAC unit and the thermal storage device. 